AISC LRFD 1.pdf

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Sect. I3.] FLEXURAL MEMBERS 45welded either through the deck or directly to the steel beam. Stud shear connectors,after installation, shall extend not less than 1 1 2-in. (38 mm) above the topof the steel deck.The slab thickness above the steel deck shall be not less than two in. (50 mm).5b. Deck Ribs Oriented Perpendicular to Steel BeamConcrete below the top of the steel deck shall be neglected in determining sectionproperties and in calculating A c for deck ribs oriented perpendicular to the steelbeams.The spacing of stud shear connectors along the length of a supporting beam shallnot exceed 36 in. (915 mm).The nominal strength of a stud shear connector shall be the value stipulated in SectionI5 multiplied by the following reduction factor:0.85 ( w (I3-1)r / hr )[( Hs / hr) −1.0]≤1.0Nrwhereh r = nominal rib height, in. (mm)H s = length of stud connector after welding, in. (mm), not to exceed the valueh r + 3 in. (75 mm) in computations, although actual length may be greaterN r = number of stud connectors in one rib at a beam intersection, not to exceedthree in computations, although more than three studs may be installedw r = average width of concrete rib or haunch (as defined in Section I3.5a), in.(mm)Where there is only a single stud placed in a rib oriented perpendicular to the steelbeam, the reduction factor of Equation I3-1 shall not exceed 0.75.To resist uplift, steel deck shall be anchored to all supporting members at a spacingnot to exceed 18 in. (460 mm). Such anchorage shall be provided by stud connectors,a combination of stud connectors and arc spot (puddle) welds, or other devicesspecified by the designer.5c. Deck Ribs Oriented Parallel to Steel BeamConcrete below the top of the steel deck may be included in determining sectionproperties and shall be included in calculating A c in Section I5.Steel deck ribs over supporting beams may be split longitudinally and separated toform a concrete haunch.When the nominal depth of steel deck is 1 1 2-in. (38 mm) or greater, the averagewidth w r of the supported haunch or rib shall be not less than two in. (50 mm) for thefirst stud in the transverse row plus four stud diameters for each additional stud.The nominal strength of a stud shear connector shall be the value stipulated in SectionI5, except that when w r /h r is less than 1.5, the value from Section I5 shall bemultiplied by the following reduction factor:0.6(w r / h r )[(H s / h r ) 1.0] 1.0<strong>LRFD</strong> Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION(I3-2)
46 FLEXURAL MEMBERS [Sect. I3.where h r and H s are as defined in Section I3.5b and w r is the average width of concreterib or haunch as defined in Section I3.5a.6. Design Shear StrengthThe design shear strength of composite beams shall be determined by the shearstrength of the steel web, in accordance with Section F2.I4. COMBINED COMPRESSION AND FLEXUREThe interaction of axial compression and flexure in the plane of symmetry on compositemembers shall be limited by Section H1.2 with the following modifications:M n = nominal flexural strength determined from plastic stress distribution onthe composite cross section except as provided below, kip-in. (N-mm)P e1 , P e2 = A s F my / 2 c elastic buckling load, kips (N)F my = modified yield stress, ksi (MPa), see Section I2 b = resistance factor for flexure from Section I3 c = resistance factor for compression = 0.85 c = column slenderness parameter defined by Equation E2-4 as modified inSection I2.2When the axial term in Equations H1-1a and H1-1b is less than 0.3, the nominalflexural strength M n shall be determined by straight line transition between thenominal flexural strength determined from the plastic distribution on the compositecross sections at (P u / c P n ) = 0.3 and the flexural strength at P u = 0 as determined inSection I3. If shear connectors are used at P u = 0, they shall be provided wheneverP u / c P n is less than 0.3.I5. SHEAR CONNECTORSThis section applies to the design of stud and channel shear connectors. For connectorsof other types, see Section I6.1. MaterialsShear connectors shall be headed steel studs not less than four stud diameters inlength after installation, or hot rolled steel channels. The stud connectors shall conformto the requirements of Section A3.6. The channel connectors shall conform tothe requirements of Section A3. Shear connectors shall be embedded in concreteslabs made with ASTM C33 aggregate or with rotary kiln produced aggregates conformingto ASTM C330, with concrete unit weight not less than 90 pcf (1 440kg/m 3 ).2. Horizontal Shear ForceThe entire horizontal shear at the interface between the steel beam and the concreteslab shall be assumed to be transferred by shear connectors, except for concrete-encasedbeams as defined in Section I1. For composite action with concretesubject to flexural compression, the total horizontal shear force between the pointof maximum positive moment and the point of zero moment shall be taken as thesmallest of the following: (a) 0.85f c A c ; (b) A s F y ; and (c) Q n ;where<strong>LRFD</strong> Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION
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LOAD AND RESISTANCEFACTOR DESIGNSPE
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iiCopyright © 2000byAmerican Insti
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vTABLE OF CONTENTSSYMBOLS . . . . .
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TABLE OF CONTENTSviiSPECIFICATION (
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TABLE OF CONTENTSixSPECIFICATION (C
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TABLE OF CONTENTSxiCOMMENTARY (Cont
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SYMBOLSxviistrength (for those stee
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SYMBOLSxixS eff Effective section m
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SYMBOLSxxit s Web stiffener thickne
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xxiiiGLOSSARYAlignment chart for co
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GLOSSARYxxvEffective moment of iner
Page 28 and 29: GLOSSARYxxviiLateral bracing member
Page 30 and 31: GLOSSARYxxixPost-buckling strength.
Page 32 and 33: GLOSSARYxxxiStrain-hardening strain
Page 34 and 35: 1CHAPTER AGENERAL PROVISIONSA1. SCO
Page 36 and 37: Sect. A3.] MATERIAL 3Cold-Formed We
Page 38 and 39: Sect. A3.] MATERIAL 5ASTM A449 bolt
Page 40 and 41: Sect. A6.] REFERENCED CODES AND STA
Page 42 and 43: Sect. A7.] DESIGN DOCUMENTS 9tion A
Page 44 and 45: Sect. B4.] STABILITY 11(a) When the
Page 46 and 47: Sect. B10.] PROPORTIONS OF BEAMS AN
Page 48 and 49: Sect. B10.] PROPORTIONS OF BEAMS AN
Page 50 and 51: 17Chap. CCHAPTER CFRAMES AND OTHER
Page 52 and 53: Sect. C3.] STABILITY BRACING 19all
Page 54 and 55: Sect. C3.] STABILITY BRACING 214. B
Page 56 and 57: Sect. C3.] STABILITY BRACING 231.0;
Page 58 and 59: Sect. D3.] PIN-CONNECTED MEMBERS AN
Page 60 and 61: 27Chap. ECHAPTER ECOLUMNS AND OTHER
Page 62 and 63: Sect. E4.] BUILT-UP MEMBERS 29(a) F
Page 64 and 65: 31Chap. FCHAPTER FBEAMS AND OTHER F
Page 66 and 67: Sect. F1.] DESIGN FOR FLEXURE 33Lp=
Page 68 and 69: Sect. F2.] DESIGN FOR SHEAR 35Lpd
Page 70 and 71: 37Chap. GCHAPTER GPLATE GIRDERSI-sh
Page 72 and 73: Sect. H3.] ALTERNATIVE INTERACTION
Page 74 and 75: Sect. I2.] COMPRESSION MEMBERS 41ti
Page 76 and 77: Sect. I3.] FLEXURAL MEMBERS 434. Lo
Page 80 and 81: Sect. I5.] SHEAR CONNECTORS 47A c =
Page 82 and 83: 49Chap. JCHAPTER JCONNECTIONS, JOIN
Page 84 and 85: Sect. J1.] GENERAL PROVISIONS 518.
Page 86 and 87: Sect. J2.] WELDS 53Welding ProcessT
Page 88 and 89: Sect. J2.] WELDS 55For end-loaded f
Page 90 and 91: Sect. J2.] WELDS 57Types of Weld an
Page 92 and 93: Sect. J3.] BOLTS AND THREADED PARTS
Page 100 and 101: Sect. J4.] DESIGN RUPTURE STRENGTH
Page 102 and 103: Sect. J8.] BEARING STRENGTH 69J6. F
Page 104 and 105: 71Chap. KCHAPTER KCONCENTRATED FORC
Page 106 and 107: Sect. K1.] FLANGES AND WEBS WITH CO
Page 108 and 109: For P u 0.4P yR v = 0.60F y d c t
Page 110 and 111: Sect. K3.] DESIGN FOR CYCLIC LOADIN
Page 112 and 113: 79Chap. LCHAPTER LSERVICEABILITY DE
Page 114 and 115: 81Chap. MCHAPTER MFABRICATION, EREC
Page 116 and 117: Sect. M4.] ERECTION 83(2) Bottom su
Page 118 and 119: Sect. M5.] QUALITY CONTROL 85The fa
Page 120 and 121: Sect. N3.] EVALUATION BY STRUCTURAL
Page 122 and 123: 89App. BAPPENDIX BDESIGN REQUIREMEN
Page 124 and 125: App. B5.] LOCAL BUCKLING 914kc=h/tw
Page 126 and 127: App. B5.] LOCAL BUCKLING 93é0.877
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App. E3.] DESIGN COMPRESSIVE STRENG
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App. F1.] DESIGN FOR FLEXURE 97For
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App. F1.] DESIGN FOR FLEXURE 99TABL
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App. F1.] DESIGN FOR FLEXURE 101Cri
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App. F3.] WEB-TAPERED MEMBERS 103j
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App. F3.] WEB-TAPERED MEMBERS 105Fw
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107App. GAPPENDIX GPLATE GIRDERSThi
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App. G3.] DESIGN SHEAR STRENGTH 109
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App. G5.] FLEXURE-SHEAR INTERACTION
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App. H3.] ALTERNATIVE INTERACTION E
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115App. JAPPENDIX JCONNECTIONS, JOI
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App. J3.] BOLTS AND THREADED PARTS
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App. K2.] PONDING 119æçMetric:lC
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App. K3.] DESIGN FOR CYCLIC LOADING
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NUMERICAL VALUES 141TABLE 2ItemShap
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NUMERICAL VALUES 143Klr123456789101
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NUMERICAL VALUES 145TABLE 3-50Desig
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NUMERICAL VALUES 147TABLE 4Values o
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NUMERICAL VALUES 149TABLE 5 (cont
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NUMERICAL VALUES 151TABLE 7Values o
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NUMERICAL VALUES 153f vVAwnTABLE 8-
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NUMERICAL VALUES 157hf vVAwnTABLE 9
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NUMERICAL VALUES 161ht wf vVAwnTABL
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163COMMENTARYon the Load and Resist
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Comm. A2.] TYPES OF CONSTRUCTION 16
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Comm. A3.] MATERIAL 167and Chen, 19
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Comm. A3.] MATERIAL 169than the ant
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Comm. A4.] LOADS AND LOAD COMBINATI
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Comm. A5.] DESIGN BASIS 173where =
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Comm. A5.] DESIGN BASIS 175( )bsln(
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177Comm. BCHAPTER BDESIGN REQUIREME
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Comm. B5.] LOCAL BUCKLING 179(c) Al
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Comm. B5.] LOCAL BUCKLING 181load.
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Comm. B7.] LIMITING SLENDERNESS RAT
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Comm. C1.] SECOND ORDER EFFECTS 185
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Comm. C1.] SECOND ORDER EFFECTS 187
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Comm. C2.] FRAME STABILITY 189Buckl
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Comm. C2.] FRAME STABILITY 191Notes
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Comm. C2.] FRAME STABILITY 193Where
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Comm. C3.] STABILITY BRACING 195age
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Comm. C3.] STABILITY BRACING 197pla
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Comm. C3.] STABILITY BRACING 199The
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Comm. C3.] STABILITY BRACING 201Par
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203Comm. ECHAPTER ECOLUMNS AND OTHE
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Comm. E4.] BUILT-UP MEMBERS 205TABL
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Comm. F1.] DESIGN FOR FLEXURE 207ha
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Comm. F1.] DESIGN FOR FLEXURE 2092b
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Comm. F4.] BEAMS AND GIRDERS WITH W
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Comm. H2.] UNSYMMETRIC MEMBERS AND
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Comm. I2.] COMPRESSION MEMBERS 215d
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Comm. I3.] FLEXURAL MEMBERS 217may
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Comm. I3.] FLEXURAL MEMBERS 219The
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Comm. I3.] FLEXURAL MEMBERS 221wher
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Comm. I3.] FLEXURAL MEMBERS 223proc
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Comm. I4.] COMBINED COMPRESSION AND
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Comm. I5.] SHEAR CONNECTORS 227tal
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229Comm. JCHAPTER JCONNECTIONS, JOI
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Comm. J1.] GENERAL PROVISIONS 231 P
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Comm. J2.] WELDS 2332b. Limitations
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Comm. J2.] WELDS 235When longitudin
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Comm. J2.] WELDS 237due to cyclic f
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Comm. J2.] WELDS 239(b) Plane 2-2,
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Comm. J3.] BOLTS AND THREADED PARTS
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Comm. J4.] DESIGN RUPTURE STRENGTH
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249Comm. KCHAPTER KCONCENTRATED FOR
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Comm. K1.] FLANGES AND WEBS WITH CO
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Comm. K1.] FLANGES AND WEBS WITH CO
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Comm. K2.] PONDING 255Even on the b
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257Comm. LCHAPTER LSERVICEABILITY D
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Comm. L5.] CORROSION 259orthotropic
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Comm. M4.] ERECTION 261It is sugges
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Comm. N4.] EVALUATION BY LOAD TESTS
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Comm. N5.] EVALUATION REPORT 265N5.
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267Comm. A-EAPPENDIX ECOLUMNS AND O
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Comm. App. F3.] WEB-TAPERED MEMBERS
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271Comm. A-GAPPENDIX GPLATE GIRDERS
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273Comm. A-KAPPENDIX JCONNECTIONS,
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Comm. J2.] WELDS 275found to be con
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Comm. K3.] DESIGN FOR CYCLIC LOADIN
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279ReferencesAckroyd, M. H., and Ge
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REFERENCES 281Bjorhovde, R. (1972),
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REFERENCES 283Fielding, D. J., and
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REFERENCES 285Johnson, D. L. (1985)
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REFERENCES 287Ollgaard, J. G., Slut
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REFERENCES 289Zhou, S. P., and Chen
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SUPPLEMENTARY BIBLIOGRAPHY 291Kotec
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Metric Conversion Factors for Commo
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